Autogenous pyrometallurgical production of nickel from sulfide ores



Dec. 18, 1962 P. E. QUENEAU ETAL 3,069,254

AUTOGENOUS PYROMETALLURGICAL PRODUCTION OF NICKEL FROM SULFIDE CRES 2Sheets-Sheet 1 Filed Aug. 23. 1960 PAUL E. QUENEAU LOUIS S. RENZONIINVENTOR C. (am

ATTORNEY Dec. 18, 1962 P. E. Qur-:Nl-:Au ETAL v 3,069,254

AUTOGENOUS PYROMETALLURGICAL PRODUCTION 0F NICKEL FROM SULFIDE ORESFiled Aug. 23, 1960 2 Sheets-Sheet 2 L.' coPPERRlcH J soLvENT l *,/44

l 3o I 43 \}7`J 30/ N i 43 I I NN U 39 x38 NICKEL L V suLFlDE @7 4 FIG.3

PAUL E .QUENEAU LOUIS S. RENZONI INVENTOR.

ATTORNEY United States Patent ilice .3506952.54 t. AUTQGENOUS`PYR0MlE'IALLURGICAL PRODUC- M TIN F NICKEL FROM SULFIDE GRES Y p P'i'ilEtienne Queneau, Fairfield, Conn., and Louis Secondo Ranzani, CopperCliiLOntarQCanad, s'sig'ito The International Nickel Company, Inc., New

York; N.-Y a corporation of Delaware p Filed' Ang.1 2s, 1960, ser. No.51,438 1-2V Claims.` (014752-282) The pre-sent invention relates' to an"improved process for' the smelting` `and reii'ning of nickel- `andcopper-containing sulfide materials for the direct recovery .of metallicnickel or nickel-copper y'alloys therefrom.

Attempts have been made yin the past to produce metallic nickel directlyfrom nickel-containing matte. Thermodynamically and kinetically thereact-ions between nickel suIlide, oxygen and nickel oxide in aconverter allow full conversion of nickel mattei to metallic nickel.Although entirely feasible theoretically, an operable process basedon-thesefreactionshas not heretofore been developed.

Borchers was perhaps the rst to attempt to blow nickel matte' to metalemploying an oxygen blast, but because' of` lack oftemperature controland improper gasliquid-solid contact he was unsuccessful. We arefamiliar with the pioneer workof Lel'lep on the desulfurizing of nickelvmatte and' nickel-copper matte` to metallic nickel and nickel-copperalloys, respectively, by blowing in a converter. Lellep consideredsurface blowing in an elo'r't to solve .the insuperable problems whichhe encountered when employing submerged tuyere's at the hightemperatures he was attempting-to use. Lellepdid not appreciate,however, the absolute necessity for ellicient gas-solidliquidcontactessential for bath' uniformity and achieve'- ment of equilibriumbetweentheseveral reactants' and the overriding advantages of usingoxygenor cxygenated air. yInstead he neglected the Vadvantages which arederived fromV mechanically' induced bath turbulence and he resorted .topreheatedV air or to extraneousheat fromA- oil, coalor electric energy,andiinally reliedV upon the' standard `Bes-semer` steel converter for.attempted application of his process. l Following the` failu-reofLellep, Shottstall e-tl al. did further work onimproving thebesseine'rizing of nickel-containing mattes to desulfuriz'e` suchmattes. They attempted to` accomplish -this"byv forcing super-heatedsteam through .themolten' matteI employing submerged tuyerefs but theirprocess was impractical. Shoistall` et al. valso fai-led to recognizethe necessity of proper gas-liquid-fsolid contact and of' the advantagesof usinga gasirich in oxygen relative to air.

The Bessemer converter isiernployedinithe'copper` in# dustry. to convertcopper sulideto metalliccopper.n In' converting nickel-bearing'ironsulfide `in the m'oltenstate to low iron-nickel sullide, theartalsodepends on the use' of` the Bessemer concept' involving` anVairblastbe-v low themolten matte level through tuyeres.V However, it-isimpossible toA blown nickel sulde to metallic nickel in this manner.Forthis purpose thekairV must be-'highly preheated or oxygena-ted orfuel must'be Ialledto* maintain the required reactiomtemreratures.However, such modification of the-Bessemer principle isimpracticalbecause of resulting. excessive localizedtemperature rise and4refractory attackQ. inadequate gas-.solid-liquid cont'act' withresulting non-uniformity of the bath, fmassive, localized nickeloxideaccumulations and inadequate control of op'eratingvariables. i

Althoughl Lellep', Shoffstall and' others madel attemptsl t-o overcomethese"an'd other di'iiicul'ties, they were'un'- able to Ldevelopacommercially operable process. p

We have nowdiscovered'th-at sulfide' materials rich in nickel,suclriasores, concentrates and lmatter, may, after 3,069,254 PatentedDec;` 1,8,r 1962 preliminary preparation, if necessary, be successfullyconverted autogenously and directly to metallic nickel by the use of anoxygen-rich stream directed' onto' these materials, at least -a portionof which are; in the molten state" while providing efficient andeffective gas-liquidsolid contact throughout the bath, Le., by inducedturbulence and controlling oxygen supply and temperature. Furthermore,another critical deficiency in the prior'art which prevented continuousliquid phase production of metallic nickel was the inability to removethe copper which is normally associated with the sullide oresof nickel;We have also discovered that such copper may be continuously separatedfrom nickel by a' major imiprovement in the obsolete and' abandonedOrford process.

It is an object of .the present invention to provide a process for theautogenous pyrometallurgica'l production of nickel or nickel-copperalloys from' nickel-copper sullide mattes. x

Another object of thetinvention is to provide a method fo'r producingmetallic nickel directly from nickelfrich sulde materials such .asmattes by inducing turbulence of the liquid material and by impingingprocesst gases ont-he physically andcheriicallyV active surface thereof.

The invention also contemplates providing novel process for the directreduction of substantially iron-free nickel matte's to nickel metalfanodes. n

lThe invention further contemplates providing` novel methods forseparatingcopper and cobalt from low iron'- nickel mattes and forreducing `the nickel suhide directly to metallic nickel.v y

It is a further object of the .inventionA to provide' an autogenousmethod *for* eliminating rock, iron and sulfur from nickel'rich `sullideconcentrates such as petlandite concentrates and obtaining nickel metalVlow iii copper, cobalt and precious metals and .a sulfurdioxide-rich'gas suitable for economic sulfur fixation;

Other objects and advantages will become apparent yfrom 'the followingdescription' taken' in' conjunction with the; accompanying' drawing in'which FIGUREV l .shows4 a. longitudinali section through' a". rotarykiln-typefurnace viny which the" autog'en-onsV smelt'-` ingf anddesulfuriz'ing of` nickel=rich sulfide materials t metallic nickelaccording to the hereindes'crifbed' process may be: carried out;`

AVFIG., 2;,depicts a cross-section' of the saine" furnace through line 22 of' FIG. l; and' FIG. 3 shows'a'diagrammatic!cross-section through aliquid-liquid extraction column ili'which copper maybe separatedfrom-nickelV sulfides by the special solventy extraction` processdescribed hereinafter.'

yAccording to the presentir'ivention,"nickel-containing sulfide'materials such as* nickelA matte andv crud nickel sulfideprecipitatessuch as "those obtained by ore'wleachiig techniques aresmelted autogenously in arotarykilriltyp furnace to a matte, Thisis'followed'bytop-blowi gth matte so obtained'in thesame"autognous,"rotaryfkiln; type' furnace using commercial oxygen' orxygeii-eh-` riched air directed' down onto the surfaceofthe'nlioltenbath butI not throughgthe metal frombelow' theliquid leveh By-'propercontrol of Voxygen supplyand'bathtem peratnre and bystrong-mechanically-induced agitation of-the bathwthe molten nickelsulde is reduced ,to sub-V staritdially" sulfur-free nickel metal. Theblowing' and mechanical agitation of the bath are controlled'each in`dependent of Athe other. Control `of oxygen ,supplyf and of turbulenceis such las to maintain satisfactory' bath iluidity land uniformityA ltopermit rapidj 4nickel sulfidenickel oxide reaction and high efficiencyof oxygen utiliza. tionl while maintaining the' temperature below, thatat whichundueirefractory attack isI experienced. Whenthe sulfurcon'teiit has been decreased Ato" less thanabout 4%' and'at'whichtiinsutlicient oxygen'is normally present in the bath to oxidize thissulfur, the blast is replaced by oxygen-impoverished gases, i.e., gaseshaving an oxygen content insufficient to cause visible formation ofinterfering amounts of nickel oxide dross on the surface of the agitatedbath. It is critically important that such gases be at such a hightemperature as to permit bath temperature regulation in the 3000 F. to3200 F. range. A-t the same time, strong mechanically-induced agitationis continued or increased in intensity to maintain eicient and effectivegas-solid-liquid contact throughout the bath. The turbulence in the bathis mandatory to insure bath uniformity, both physical and chemical, soas to give quick reaction towards equilibrium, e.g., the nickeloxidenickel sulfide reaction. By this technique sulfur in the moltenbath may be eliminated to less than about 0.05% sulfur, e.g., 0.01%sulfur. It will be understood of course, that alternatively standarddesulfurization techniques can be employed for final sulfur removal.

Agitation of the bath to insure adequate gas-liquidsolid contact isobtained by rotating the furnace and by blowing the oxygen-rich gasstream onto the turbulent molten bath from above the liquid level. Ithas been found that the blowing operation may be conducted initially attemperatures not greatly above the melting point of the nickelsulfide-containing material and at this stage advantage is taken of theexothermic heat of reaction to smelt solid feed if desired. However, itis preferred to heat the nickel sulfide to a temperature of at leastabout 2400 F., avoiding formation of surface oxide, under weakly ornon-oxidizing conditions prior to blowing with commercial oxygen. If nomelting is to take place and molten matte at elevated temperature isavailable, proper rate and degree of heating can be achieved by controlof oxygen addition. The temperature is raised as desulfurizationproceeds until, at a sulfur content of the bath of less than 4%,advantageously between about 1% and about 3%, a temperature betweenabout 3000 F., and 3200o F., is attained and maintained until finalsulphur elimination is achieved. It will be understood that if thenickel contains a substantial proportion of copper, final ytemperatureswill be significantly lower.

In carrying one embodiment of the invention into practice, nickel matte,which may contain less than about 1% iron, the amount of copperremaining after conventional separation of copper by ore dressing means,e.g., one part of copper to ten parts of nickel, and some cobalt andprecious metals, e.g., one part of cobalt to 25 parts of nickel and 2ounces of precious metals per ton of nickel, is treated, if desired, forthe removal of the copper, cobalt and precious metals as hereinafterdescribed. The matte is then transferred to the autogenous reductionfurnace wherein it is top blown with oxygen to nickel metal.

The autogenous reduction operation may be carried out in the furnacedepicted in FIG. l and FIG. 2 of the accompanying drawing which show alongitudinel section of the furnace and a cross-section of the furnacethrough line 2-2 of FIG. 1, respectively. Referring to FIGS. 1 and 2,the molten, nickel sulfidecontaining material is treated in a rotarykiln-type furnace 11 which is lined with high-grade refractory brick 12.The furnace may be tilted as desired for tapping by using tiltingmechanism 20. The furnace has tires or drive rims 13 aixedcircumferentally around it and these tires rest on supporting or drivewheels 14. Oxygen or oxygen-enriched air is supplied by a water-cooledtube or pipe 15 which projects through seal 21 and opening 16 into thefurnace. Exhaust gases pass out of opening 17 at the other end of thefurnace into the flue 18 which may be water-cooled and which may beswung away from the kiln opening to allow charging of fresh sulfide,flux or other materials through opening 17. Solids may be alternativelycharged through opening 16 upon removal of pipe 15 and seal 21. Seal 22provides a gas-tight contact between the kiln and ue 18. Slag may bewithdrawn by tilting the furnace and tapping from the top of the moltenbath. At the completion of the blow, molten metallic nickel is tapped bytilting the furnace into the position shown by 23 in FIG. 1 or isoptionally withdrawn through taphole 19.

The reduction operation need not be conducted in the apparatus asspecifically shown in FIG. 1 and described hereinbefore providing theapparatus meets the operational requirements as outlined herein, e.g.,it may be carried out in a top blown converter such as the Kaldofurnace.

Based on tonnage tests, which we have conducted, we estimate that asingle furnace of the above-described design, with effective insidediameter of about 17 feet, can produce commercial nickel at the rate ofabout 500 tons per day.

Nickel matte which is substantially iron-free may be blown directly tometallic nickel after copper removal, if necessary, from the moltenmaterial as described hereinafter. Precious metals may be removed asdescribed hereinafter before blowing directly to metallic nickel.

The sulfide material which has been charged into the furnace is treatedby bringing oxygen or oxygen-enriched air into direct contact with itssurface. This gas, which advantageously is initially commercial oxygen,is blown into the furnace above the surface of the molten material.Necessary bath turbulence is maintained by continuous rotation of thefurnace at a substantial speed.

In the first stage of the blow the temperature of the bath is kept highenough to keep the reacting materials in a sufficiently fluid state topermit rapid reaction and yet below the temperature at which unduerefractory penetration or erosion is experienced. For relatively purenickel matte which melts at about l450 F., the furnace blow may bestarted at a temperature of as low as 1550 F. However, in mostcircumstances it is preferred to initiate the blow with commercialoxygen at much higher temperatures than 1550" F., e.g., 2500 F., inorder to avoid formation of nickel oxide slag and accretions. Forsullides containing substantial amounts of iron as well as nickel, suchas pentlandite concentrate, and which require considerable slagging offof iron, the temperature must be high enough to keep the slag in a fluidstate.

It is important that substantially all iron is eliminated and any slagis removed from the furnace before blowing for sulfur removal to formmetallic nickel is commenced. It has been found that any formation ofslag during reduction of the nickel matte to metallic nickel results inserious decrease in gas-liquid contact and lowers oxygen efficiency.Thus, only by keeping the surface of the molten bath reasonably clear ofslag is economic desulfurization in the autogenous reduction furnacepossible.

As sulfur elimination of the bath by the top blowing with oxygen oroxygen-enriched air proceeds, the temperature of the bath is rapidlyraised until the sulfur content of the bath has been lowered topreferably between about 1% and about 3% and a bath temperature of morethan about 2800 F. has been attained. It has been found that thetemperature of the reduction operation and, in fact, the operation ingeneral is controlled by varying the oxygen supply, by observing exhaustgas analysis and temperature and by varying turbulence.

During this first stage of sulfur elimination down to between about 1%and about 3% sulfur, it is preferable to inject as much oxygen as ispracticable without causing undue nickel oxide slag formation or toomuch splash formation at the mouth of the furnace. Use of commercialoxygen allows more rapid nickel reduction and production of gas rich insulfur dioxide, e.g., 75% sulfur dioxide, but excess heat is alsothereby generated. Part of this heat is utilized for heating the chargeto the temperature desired for final sulfur elimination, i.e., betweenabout 3000 F. and 3200 F. It may be desirable to cool by injecting airinto the furnace. The addition of air may be, of course, undesirable inlowering the sulfur dioxide content in the exhaust gas and increasingthe gas quantity required per unit volume of injected oxygen.,

Cooling may be otherwise accomplished or may be supplemented by addingwater to the gas stream rather than air or by adding solid charge to4the furnace or by a combination of these techniques.

When desulfurization has proceeded to preferably -between about 1% andabout 3% sulfur, eg., 2% sulfur, the. oxidizing. gases. should be.replaced, as. aforestated, by substantially sulfur-freeoxygen-impoverished gases, e.g., neutral or somewhat reducing gaseswhile heating or maintaining the molten. bath to a temperature ofbetween `about 3000 F. andV about 3,200o F. To maintain this temperaturein the bath, the neutral or reducing gases must be at; a hightemperature and this is best accomplished by adding aV highlycombustible.` fuel such as natural gas on propane together with theoxygen. The fuel consumes any excess oxygen and generates a hightemperature flame so that undue formation of nickel oxide isthereby`prevented.. Theimpinging gases may thus advantageouslyI and. graduallybe decreased in. oxygen content from that of comercial. oxygen, to:oxygen-enriched f air., to air; to oxygen-impoverishment, tonon-oxidizing or inert. and finally: to somewhat reducing. It will beunderstood that, once. adequate oxygen supply is present in the bath,the functionof the impinging gases. is heat supply and; insurance` of alow sulfur dioxide partial pressure atmosphere. The. exact oxygenIcontent of the. gas is` variable determined. by and` within the.control: of the furnace operator.; It has been: found that during thisfinal desulfurization periodbest resultsV are obtained by.increasingbathturbulence; especially if for any reason the bath: hasVbecome over-oxidized:

By the above: noveltechnique', desulfurization of the lmolten' nickel'proceeds. to` less than 0:05.% sulfur, eigz, 0.01%y sulfur. Blowing'ofmolten nickeli sullidefmaterial down to these. lowgsulfur contents on attonnage basis has been'foundto'be` attainable in less than 81hours.

FinaL desulfrization, which` isv carried. out. under al neutral'` or.Vsomewhat reducing atmosphere, is essentially achieved; by reaction.between residual sulfur.` and oxygen in the molten metal. Asurprisinglyhigh. absorption'off oxygen takes placei in our-metal bath beforeany'visibleA oxide lm on its. Vsurface appears. Thus, inione case, arrapparent dissolved oxygen content of 9.5% was obtained while the metalwas at a temperature of 3100o F., which is a much highercontent-than-expected from study of the nickel-oxygen equilibriumdiagram. We believe a substantial proportion of f this i oxygen wasypresent as anA extremely nely-divided', uniformlyY dispersed, solidnickeli oxide. phase. Highoxygen. content in the sulfur-bearing bathy isaikeyt featurelofour turbulent metal desulfurizing process in4 that. itpermits' elimination. of the: oxidizing: furnace.- atmosphere at amuclr`higher sulfur; contentiof' themetalbath than in'the prior art.. Theoxygenlcontent of the bath required for effective final desulfurization,of course, neednot` be as-high asthe above. Sulfur isyprefl erably,eliminatedlwithout formingwisible oxide floating; on the surface, `i.e.,temperature and oxygen additionzis' so controlled as to maintain a shinysurface on the metal bath. Speed of rening increases the higher theoxygen content of the bath without surface oxide formation, e.g.,without substantial clouding of the bath surface.

Asastatedhereinbefore, the surface `of the molten bath shouldbekept freeof slag or scum. For this purpose the oxidizing gasesinthe furnaceApreferablyshould' be replaced by, nonfoxidi'zing gases before sulfur..elimination; has proceeded tofbelwaboutl%-sulfur; e.g.^, 2% sulfur:Deoxidation ofsthe molten bathaftersulfur" removal may be readilycarried out .by carbon addition to the furnace. Graphite has beenfoundto be an excellent deoxidizing agentcalthoughother: deoxidantsfsuch'asisilicon or'aluminum .mayl be utilized. A highresidualIoxygencontentfin theibathl should; of course, be `avoidedsince'large quanti* ties oficostly deoxidizing` agents ,are requiredand`possiblyy violent; reactions may foccur;

In a modiied procedure for carrying out the reduction' of' nickel -suldeto metallic nickel by" our novel tech niques the finaldesulfur'izationvr from below 4% sulfur is` carried out in a separatefurnace in the same manner' as described hereinbefore.y This modifiedprocedure may be advantageous over doing` the complete operation in onefurnace. Thus, lfinal refining' may' be carried out in a furnace thewalls of which are' not impregnated with sulfide which has the: effectof delaying the lowering of -sulfur content in the bath and alsopresents a risk= of re-absorption, ifi deoxidation is carried out insidethe furnace before tapping.V There is a further advantage in using asecondfurnace. in that brick which is not impregnated with sulfide' willallow increased refractory strengthl `at the; high temperature necessaryduring final desulfurization. Furthermore, the two furnaceI techniquewill allow steady' operation in one? furnace which is utilizing oxygenonly and so attain an even. produc'- tion of gas with a. high sulfurdioxide content produced while usingf the second' furnace which isiutilizing oxygenimpoverished gases with. generally more rapid furnacerotation. Also;` any oxide formedr in theV first furnace could beeasilyretained therein' for subsequent reaction with green charge, with the`final blow in the second furnace. being carried out without risk ofslag. formation,`

It is to be noted that the herein described novel reduction of. nickelY-sulde to metallic nickel can be attained with very smalll nickellossesdue either to slagging as oxide; or. to'dustingin exhaust gases, i.e.,``a nickely yield' in excess of 99%. We have produced nickel by ourprocess on a tonnage basis containingv 0.009% sulfur, 0.02%- silicon,0.00-l7% lead, 0.000l% zinc 0\.0`004%l bismuth andl 0.0014.% antimony.

The extremeimportance and: necessity connected strong. inducedturbulence of.r the furnace bath as described hereinbefore, isdemonstrated. by the failure to obtain the desired results by blowing in`a stationary' furnace as shown in Example VII described hereinafter inwhich the nickel reduction reaction ceased" at a sulfur content of 2% inthe bath due Ito excessive locali oxidationand resultant formation of' afloating impenetrable, hard, nickel. oxide blanket. A similar resultisobtained if attempts are made to. reduce the sulfur content of the bathto below about 1% sulfur before replacing the oxygen with hightemperature,-weakly oxidizing, nonoxidizing, neutral and7or reducinggases which we have termed oxygenLii-npover-ished' gases and which havean oxygen content insufficient to cause` visible frmationof interferingamounts of nickel oxide' dross on the l surface ofV the f agitated bath,e'.g=, with ai free oxygen= content' of less than about 3%. In caseswhereA iron-containingv nickel nlatteis-ii1'st'v blown in tlievautogenous reduction furnace'forironremoval, theslag formedV istreatedfon recovery of" its nickelE content. dvantageously, slagjproduced during the first stage of iron eliminationwliicli is low innickel i-s removed and treated for recovery of its nickel content, ifdesired)A and the slag producedduringrthefmal-stage.oflironeliminationisleft.in thecfumace. for.recovery of itsinicke'l content upon further addition of'lconcentrate-tori matte.M After af complete charge of molten matterhas-'been built up in the autogenous furnace, slag produced from finaliron elimination is removed and Imay be. treatedV in parallel'autogenous reduction furnac'effor treatment with;v fresh sulfide.

In the `instances where nickel sulfide-materialsto b'eAL treated lby,this process contain `amounts offcopper or cobalt which may not beacceptable in the nickel metal, eag.,.. more than. a'bout.0."10!%iAcopper fand/.or moreA than aboutl0.75% cobalt in thezimetal, the-sulfrdetmaterial must be .processed for"y their removal.

The copper advantageously should:;be removed before` desulfurizing.treatmentv in the top blowna: reduction furnace.l`Coppersremoval..byfmeans ofsa novelsolvent extraction process, ie., hightemperature liquid-:liquid extraction, has been found particularlyadvantageous. By this technique we have found that nickel sulfide with asubstantial copper content, e.g., a ratio of nickel:copper of, forinstance, 10:1 can be treated for copper .removal to produce a nickelsulde having a residual copper content of less than 0.10%, e.g., with aratio of nickelzcopper of at least about l000:1. As a general rulenickel sulfide ores containing copper can be concentrated by flotationso that the bulk of the nickel is in a concentrate containing nickel andcopper in a ratio of at least about 10:1 which can be readilydecopperized by our novel procedure. Much higher copper contents can beextracted by this method if simpler prior separation, eg., of thenatural minerals by flotation, is impractical.

This novel molten salt solvent extraction technique is based on the useof sodium sulfide as the selective agent, probably a complexing agent,for copper sulfide. This agent is dissolved in molten sodium chloride inwhich solution nickel has only a slight solubility and copper a highsolubility. An essential feature of this salt cornbination is itsrelatively low melting point of below about 1300 F. This permits thesolvent extraction to proceed at a temperature as low as about 1350 F.Thus, the extraction is carried out close to the melting point of themetal sulfides which is the optimum temperature for liquid copper-nickelseparation. This low operating temperature and the high water solubilityof the extractant have the additional important advantages of economy inreagent, fuel and refractories consumption.

This novel separation technique is outstanding in that sequestration ofcopper by the solvent and isolation of nickel are both highly effectivewhile the cost of labor, supplies and equipment is relatively low. Ourprocedure permits economical removal of co-pper sulfide, entirely beyondthe capability of the existing art, from sulfides having a broad rangeof nickel to copper ratios to yield nickel sulfide having a nickel tocopper ratio of greater than l000:1.

The highly beneficial effect of using a solvent, such as sodium chloridefor sodium sulfide is clearly demonstrated by the following example:

EXAMPLE I 150 grams of matte, containing 68.2% nickel and 3.25% copper,was mixed with 150 grams of sodium sulde and the mixture was melted at1550 F. The upper sodi-um-rich and the lower nickel-rich fractions weretapped from the bottom of the crucible into separate containers althoughthere was found to be no sharp physical definition between them.Analyses of these upper and lower layers gave the results as shown inTable I.

The test was then repeated except that 75 grams of sodium chloride and75 grams of sodium sulfide were used instead of 150 grams of sodiumsulfide. Two distinct liquid fractions were obtained by this test whichwere cleanly separated by bottom tapping. The two fractions were thenanalyzed to give the results as shown in Table II.

8 Table II o Total Nickel Weight, percent Ni: Cu Ratio Percent PercentCu Nl Upper Sodium-Rich Frac- In this novel liquid-liquid solventextraction technique about one-half to double by weight of a mixture ofsodium chloride and sodium sulfide may be melted with thecopper-containing nickel sulfide material. The sodium chloride-sodiumsulfide mixture advantageously may contain between about 25% and about75% sodium chloride.

It will be understood that although we prefer sodium chloride, otherchloride modifiers such as the chlorides of potassium, calcium andaluminum may be employed.

The nickel sulfide material and sodium salts are advantageously meltedat not below about 1350 F. and not above about 1550 F., carefully mixedto insure excellent countercurrent liquid-liquid contact and thenseparated by gravity into copper-rich and nickel-rich fractions. Apreferred apparatus for this purpose is a liquid-liquid extractioncolumn as shown in FIGURE 3. The substantially copper-free nickelsulfide product may be air blown for slagging of residual sodium saltsand then transferred directly to the autogenous reduction furnace to beblown to metallic nickel as described hereinbefore. The copper-sodiumrich product may be treated by water leaching to recover copper and thesodium salts and residual nickel. Alternatively, the extraction may becarried out in other apparatus, e.g., in an appropriately designed,countercurrently operated rotating kiln or by simple ladle mixing,settling and bottom pouring in a countercurrent multi-stage operation.The advantageous results obtained by our novel solvent extractiontechnique rfor extracting copper from nickel sulde are shown in ExamplesII and III.

EXAMPLE II A nickel matte containing 3.25% copper with the bal-Analysis, Percent NizCu Ratio Cu Ni Final Copper-Rich Solvent--.. 4.2U 1. 2 0.3:1 Final Nickel Sulfde 0.03 63. 3 2110:1

EXAMPLE III A nickel matte containing 4.8% copper with the balancemainly nickel and sulfur was treated for copper extraction in the sameway as in Example II except that the countercurrent extraction wasconducted at 1400 F. The final products from the four-stage treatmentanalyzed as follows:

Analysis, Percent NizCu Ratio Cu Nl Final Copper-Rich Solvent l 6.25 1.20.211 Final Nickel sulfide 0.06 i 63,3 l 105ml It has been found highlyadvantageous to use a continuous countercurrent solvent extractiontechnique to attain copper removal down toless than about 0.1% copper inthe nickel sulde material. The countercurrent liquid-liquid extractionmay takeplace in a standard type of apparatus such as that shown inFIGURE 3 which depicts. the diagrammatic cross-section of a baille platecolumn in which theV copper-containing nickel sultide is treated withthemolten salt mixture for elimination of copper. Referring` to FIGURE3, solid baffle plates. 30, which extendpartially across thecolunmcrosssection, are placed at suitable intervals in the column.Molten copper-containing nickel sulfide from storage tank 31-` isintroduced through line 32' and variable orifice 33 into the top ofthecolumn at 34. Molten sodium saltsolvent from storage tank 35 isintroduced through line- 36 and: variable orice 3l'7` into` the bottomofthe column at 3S. Nickel sulfide from whichl copper has beeneliminated. is drawn olf the. bottom of the `column throughv line 39sand. variable orice 40. Copper-rich solventis drawn off-` the top ofthecolumn-through line 41. HeatY is. supplied tothe column and` to thetanks-31 and 35' tov maintain the sulde and sodium salts in a moltencondition and at the separation temperature desired such as byway ofelectric immersion heaters 42 and external electric heaters 43;

The heavier nickel sulfide flows along eachbaille, which is. suppliedwith` a short lip 44 so that each is substantially a tray, overiiowsover the lip and then flows downward tothe next tray; The lightersodiumsalt solvent flows upwardV around each baille and throughthe freearea between the tray and the inside wallsV of the column Thus, as thesodium saltsolvent rises throughthefalling nickel sulde andremovescopper sulfide it becomes progressivelyl richer in copper-sullide, whilethe n'ckel sulfide has more and more coppersulfide extractedvv as itflowsdownward.

A; mini-plant multi-tray column of the above generalv design, 3inchesLD. by 4S` incheshigh was operated aty a feed rat-e of up to.one-half' ton per dayof copperbearingnickel4 suliideemploying asasolvent a salt4 mixture consisting. of sodiuml sulfide and sodiumchloride and containing between 25%A and 75 sodium chloride. ln.thissimple device we were able to continuously-lower the copper contentof the nickel matte in a ratio of about 110:1, producing: a nickellsuldewith a Ni:CuA ratio exceedingV 1000:1when treating'mattes in the0.75% Cu to. 3.5% copper range. The test results-vindicatedv thatnickel' suldehaving a` substantially-higher copper content, e.g., 10%copper, could also be successfully treated.

Basedr on` equilibrium dataestablished for our novel,` liquidi-liquidextractionA system in the laboratory and fur,- therv substantiated bythe above mini-plant experiments, copper reductions by weighty of 100:1or more` can be realized from cupriferous nickel' sulfide when using ourprocess` in commercial extraction equipment such as tray4 columns,-Packed` columns-.or mixer-settlers.

I-tis to b e observed that ournovel: technique for removing copperfromnickel rn-attesi before blowing tometallinickel permits a much higherdegree of copper.` elimination therefrom than can; be obtained; bycontrolled coolingt andullotation, of -thematte, ire., lessthan 0.05%Cuas comparedto morethan:y 0.50%

As. stated. hereinbefore` the. moltennickel matteY from.i whichthecopper has advantageously-been ext-racteddownt to below about 0.310%coppermay-betransferredto theV autogenpus reduction; furnace, preferablyafter residuale sodium salts, have been removed by ra brief, relativelylowtemperature, airblow in a separate vessel and decantedr for reuse.However, in cases where there. are precious` metal valuesv associatedwith the. nickel suliide material the precious metals may be removed byknown meansA such as by blowingpto create a sulfur deficiency, cooling,solidifying, grinding and removing the, precious` metals, concentratedin the metallics. The.` nickel sulfide, may then be, water leachedto.remove sodium salts, dried land then fed directlytov the autogenouslreduction kiln.

In speciall circumstances, cobalt elimination may be accomplished during4conversion of the; sulfide, material to metal by blowing the moltenmaterial with an oxygenrich gas at a sulfur content off; more than about3% to selectively oxidize the cobalt in the presence of a ilux such assilica. The cobaltr is then skimmed' off.' as slag. The sulfur contentof the molten charge is maintained at above about 3% sulfur bycontinuously adding fresh sulfide material' to the autogenous reductionfurnace while top-blowing at between about 2300-o F; and about2800 F24for sulfur :and cobalt removal'. When the furnace has receivedV ia fullcharge and' adequate cobalt removal has been achieved, the top-blowingof" the molten charge is then completed as described hereinbefore toform metallic nickel; The cobalt-rich slag can be conveniently treatedfor cobalt recovery by known means. It will3 be understood',however,vthat formation ofthisslag can interfere with our process, ashereinbefore described, so that cobalt removalY in this manner is notvalways practicable.

The following example illustrates the, satisfactory re;- sults that maybe obtained by our technique for eliminating cobalty from nickelsulfide:

illustrative examples-are given:`

EKA-MELE V A suhideorecontaining nickel; copper, cobalt;ironand-gangueminerals was treated by conventional methods to produce aconcentrate containing-12.0% nickel, 1.6%-

copper,4 0.4% cobalt, 40.0% iron, 311.0% sulfur and 7% silica.Thisconcentrate was autogenously smelted with oxygen to a mattecontaining 48.2%' nickel, 8.6% copper, 1.6% cobalt, 28% sulfurand thebalance mainly iron.

l rFheslag from this operation-containing 115% nickel' was.

removedlfor separate treatment to recover its-metallvalues. rlibe-martewas then` blown with oxygen to produce a sub-V stantially` iron-freematte which was tapped: to leave a high nickel slag in--the` furnace-forsubsequent reduction withfreshcharge. Thismatte was treated for copperremoval 'at 1400- F. by our `solvent extraction technique as`describedlhereinbefore in Example III. Theresulting substantiallyironandcopper-free matte wastreated toy remove cobalt by theprocessdescribed in Example IV; The thus-treatedf matte wasV top blownwithoxygen atI a temperature--rising-to 2850` F. 'to a sulfur content of32%'. The thus blown matte can then b e treated, as has been describedabove, forfinal sulfur elimination.

EXAMPLE VI 4:4` tonsof a` molten nickel matte containing. 70.9%v nickel,4.8% copper, 1.0% iron and 23.3% sulfur were topblown with-,oxygen in afurnace, similar to that-shown in FIGURE l2, rotating at 20'r.p.m. at atemperature rising to 3000 F. Cooling was accomplished4 by itijectingair with the oxygen. The molten material was blown down to 1.4% sulfurat which point propane gas was injected with the oxygen and rotation ofthe furnace was increased to r.p.m. Enough propane was injected toproduce a somewhat reducing atmosphere in the furnace. The temperatureof the bath rose to and was held at about 3l00 F. and the molten bathwas blown to a sulfur content of 0.02%. The bath at the end of the blowhad an oxygen content of 1.9% which was removed by adding graphite tothe bath in the furnace. Total blowing time to nal desulfurization wasseven hours and fifty minutes.

EXAMPLE VII To illustrate the extreme importance of strong mechanicallyinduced agitation of the molten bath during blowing, 4.3 tons of thesame nickel matte as treated in Example VI were blown with oxygen in amanner similar to t-hat used in these examples except that the furnaceremained stationary. After eight hours and forty minutes of blowing thesulfur content of the metal had been decreased to only 2%, furtherreaction ceased and blowing had to be discontinued because of nickeloxide accumulation with formation of a heavy impenetrable layer of slagfloating on the metal. It -is to be observed that by the above describedinvention, metallic nickel can be produced directly from nickelconcentrates obtained by flotation of nickel sulfide ores after copperremoval by our novel techniques as described hereinbefore. It is knownthat pentlandite concentrate may be oxygen-flash smelted to a nickelmatte, as disclosed by one of the present inventors in U.S. Patent No.2,668,107. Our new process is an improvement over that described in thispatent in that our product is metallic nickel instead of nickel mattewith a high impurities content. Summarizing our technique for treatingnickel concentrates by our novel process to obtain metallic nickeldirectly, we charge dry nickel concentrate, eg., pentlanditeconcentrate, into molten material in an autogenous reduction furnace,such as described hereinbefore, and blow for removal of iron which maybe slagged off by addition of siliceous flux. The slag produced duringthe first stage of iron elimination, low in nickel, is removed from thefurnace and the slag produced during the final stage of iron eliminationis left in the furnace for extraction of its nickel content upon furtheraddition of concentrate. After iron removal is completed, the moltenmaterial may be treated for copper removal and Iit is then blowndirectly to metallic nickel both of which operations are above describedin detail.

It is further to be observed that the hereindescribed process is highlysuitable for lthe treatment of crude mattes obtained from lateriticnickel-containing ores as for instance, by the process described by oneof the present inventors in the copending U.S. patent application SerialNo. 51,418, filed August 23, 1960, now U.S. Patent 3,004,846. Thesemattes which contain substantial amounts of iron and some cobalt can beblown in the autogenous reduction furnace for iron, sulfur and cobaltremoval and direct production of metallic nickel. Since these lateriticores normally contain substantially no copper Or precious metals, themolten material need not be treated for their removal but in the case ofores with a substantial cobalt content, the matte may be treated forcobalt removal as described herein.

It is to be observed also that prior art techniques for directlyreducing nickel-rich matte to commercial metallic nickel ornickel-copper alloys failed utterly because of formation of metal oxidesrather than metal with resultant massive accumulations of accretions andof floating dross which smothered the reaction long before it wascomplete and also because of destruction of refractories due tosubsurface blowing of the bath and/or lack of proper bath turbulencewith consequent excessive local temperature rise.

Furthermore, it is to be observed that our novel copper removaltechnique, by high temperature liquid-liquid separation is a majoradvance over the now long obsolete Orford process which was abandonedbecause of its high cost and the low separation efficiency of itsbatch-type operation.

This application is a continuation-in-part of our copending U.S.application Serial No. 839,431, filed September l1, 1959, now abandoned.

Although the present invention has been described in conjunction withpreferred embodiments, it is to be understood that modifications andvariations may be resorted to without departing from the spirit andscope of the invention, as those skilled in the art will readilyunderstand. Thus, our process may be employed for the treatment ofcopper-rich materials, eg., copper flotation concentrates and mattes toyield directly fire-refined or anode copper. Such modifications andvariations are considered to be within the purview and scope of theinvention and appended clams.

We claim:

1. An improved process for autogenously converting a nickel sulfidematerial to produce nickel of low sulfur content which comprisesdirecting oxidizing gases from the group consisting of commercial oxygenand oxygenenriched air into the exposed surface of a molten bath of saidsulfide material, while avoiding sidewall and bottom blowing of saidgases through the bath, and maintaining the bath during the convertingin a state of turbulence with non-pneumatic, mechanically inducedagitation, said agitation being maintained during the directing of saidoxidizing gases, to promote intimate and efficient gas-liquid-solidcontact and uniform distribution of oxygen throughout the bath and itsrapid reaction with sulfur therein; raising the bath temperature asdesulfurization proceeds to more than about 2800 F.; changing said gasesbeing introduced into the bath surface to hot, substantially sulfur-freegases from the group consisting of neutral and reducing gases having anOxygen content insufficient to cause visible formation of interferingamounts of nickel oxide dross on the surface of the bath when the sulfurcontent of the bath is still substantial but is less than about 4% andthe oxygen content of the bath is at least sufiicient to oxidize thesulfur content, the bath being at a temperature of at least about 3000oF. and maintained in a turbulent state by non-pneumatic, inducedagitation upon changing from oxygen-rich gases; and maintaining a bathtemperature of at least about 3000 F. in the presence of said hot gasesto continue the reaction between sulfur and oxygen in -the turbulentbath and to produce nickel with a sulfur content low enough below 0.5%for removal by desulfurization.

2. A process as described in claim 1 in which mechanically inducedagitation of the molten Ibath is attained by rotation of the furnace andthe metallic nickel obtained contains not more than about 0.02% sulfur.

3. An improved process for autogenously converting a nickel sulfidematerial to produce refined nickel. of low sulfur content whichcomprises blowing commercial oxygen onto the exposed surface of a moltenbath of said sulfide material While avoiding sidewall and bottom blowingof said oxygen through the bath, and maintaining the bath substantiallyslag free during the blowing with oxygen and in a state of turbulencewith mechanically induced agitation, said agitation being maintainedduring the blowing, to promote intimate and efficient gas-liquid-solidcontact and uniform distribution of oxygen throughout the bath and itsrapid reaction with sulfur therein and to produce off-gas rich in sulfurdioxide; raising the bath temperature as desulfurization proceeds tomore than about 2800 F. whileV continuing said blowing with oxygen;transferring the bath to a substantially sulfide-free furnaceenvironment when the sulfur content of said bath is still substantialbut is less annessa 13;- thanl .about 4% and its oxygen content isr atleast, suvfli-,A cient to oxidize. theY sulfur content; blowing ontosaid transferred bath, maintained` in e, state f turbulence bymechanically induced agitation, het gasesfiern. the grens consisting efneutral and reducing gases substantially free 0f sulfur dicnide andhaving en Oxygen content in-V sntiicient tc. canse visible iennationAof. interfering einennts ci nickel Oxide dress en the surface 0f tbebetln tbe transferred. beth beine at n temneretnre. cf, at leest ebbnt3Q0O l-s, maintaining a batn temperature ef at least about 3000 F; inthe presence of said hot gases to continue the reaction between sulfurand oxygen in the turbulent beth end te Obtain rnetnllic. nickel; and,dcoxidizing the molten bath to produce refined, nickel' with a lowsulfur content of not more than of; the order of about 0.05%.l

4. In a process for producing refined, metallic nickel fromv nickel-richsulfide materials containing iron in which the sulfide materialV issmelted, to produce a nickeliron matte andthe nickel-iron matte is`blown to remove iron therefrom and form a nickel matte, the improvementWwhich comprises autogenously smelting the nickel matte by blowingcommercial oxygen onto the exposed surface of a molten ba-th4 of saidnickel matte at atemperature ofV at leastabout 2400 F., whileavoidingsidewall and bottom blowing of said oxygen through the bath, andmaintainingthe'bathv 4substantially free of slag during the blowing withoxygen and in a state of turbulence with mechanically induced agitation,said agitationJ being maintained during the blowing, to promote intimateand efficientl gas-liquid-solid contact and uniform distributionofoxygen throughout the bath and its rapid reaction with sulfur therein;raising. the bathtemperaturel as desulfurization proceeds tomorethanabout 2800 F; while continuing. said blowing with oxygen; changingsaidoxygen being directed onto the molten bath to hot gases from the groupconsisting of neutral and reducinggases substantially free of sulfurdioxiden and having. an oxygen content insufficient to cause visibleformation of interfering amounts of nickel-z oxideA dross on the surfaceof the bath when its sulfur content` is between about 1% and -about 3%.`and its oxygen contentr is at least` sufficient to oxidize the sulfurcontent, the bath. being at. a temperature of'between about 3.0009 F;and' 3200"v F. and maintainedl in a turbulent state by, mechanicallynducedagit-ation upon changing from oxygen; andi maintaining -a bath,temperature of between about 3000? F` and 3200? in the presence of'saidhot gasesA to continue the reaction between sulfur and oxygen in theturbulent bathV and to, produce refined, pig nickel: with, a low sulfurcontent of; not more than ofv the order of` about 0.05%.

5. Ant autogenous process for producing refined metallic nickel directlyfrom nickel-rich sulfide materials containing iron which comprisesdirecting commercial, oxygenA onto the surface of'a molten bat-hof saidnickel-rich sulfide material while avoiding sidewall and bottom blowingof said oxygen through the bath, said bath being maintained in a stateofturbulence by mechanically in duced agitation, saidagitation beingmaintained during the directing of" said oxygen, to oxidize iron` and.desulfurize the bath; slagging the `oxidized iron with silica flux anddrawing off the slag so formed; raising the temperature of the moltenbath after slagging of said iron and as desulfurization proceeds toattain a bath temperature of at least about 2800 F., While continuingthe directing of oxygen onto the molten bath maintained in a state ofinduced turbulence to promote intimate and efficient gas-liquid-solidcontact and uniform distribution of oxygen throughout the bath and itsrapid reaction with sulfur therein; changing said oxygen being directedonto the molten bath to hot gases from the group consisting of neutraland reducing gases substantially free of sulfur dioxide and having anoxygen content insufficient to cause visible formation of interferingchanging. said; gases. berng mtroduced; into the. bath, suramounts etnickel. @aide dross on the. surface.. of the bath, when itsY sulfurcontent is. between about, 1% and. ebent 3% and` its oxygen. cententisetleast snicient te QXidize tbe snlfnr centent, the bathr being attemperature. of; et` leest nbent 300.0 1?- a nd maintained in e,turbulent state by yrnecli.en icnlr induced aaitatien nnen changingfrein Oxygen; and, maintaining, n bntb temperaturev 0f at. least about'`3000 E. in the presence of said hot gases to cmtinue the reactionbetween sulfur and oxygen in the turbulent bath and to produce refined,pig nickel with a low sulfur con-tent ofnot more than of the order o fabout 0.05%.

6`- A process as `described in claim 5A in which the nickel-rich sulfidematerial contains cobaltl and wherein, after iron is oxidized, slaggedand drawn off, the sulfur content ofthe metal bat-h is maintained atgreater than about 3% by adding fresh sulfide material while blowingwith oxygen at between about 2 300 F. andl about- 2800" F.` to oxidizethe cobalt and remove it as slag.

7i. An improved process for- -au-togenously converting a nickel-coppersulfide material to produce nickelecopperalloy of "low sulfur contentwhich comprises directingoxygen-rich gases from the group consisting ofcommercial` oxygen and oxygen-enrichedair into the. exposed sur-facetof-V a moltenf bath of said sulfide material, while avoiding sidewalland` bottom blowing ofsaid gasesA through the bath, and maintaining the.bath during the converting. in a state of turbulence. withnon-pneumatic, mechanically induced4 agitation, said agitation beingmaintained during the, directing of said oxygen-.nich gases, to, promoteintimate and efficient gas-.liquid-sc lidl contact and uniformdistribution of'A oxygen throughout therbath, 4and its rapid reactionswith sulfur therein; raising the, bath temperature as desulfurizationproceeds while` main-V. taining its surface substantially -free ofoxidedross;

face to4 hot, substantially sulfur-.free gases` from the. groupconsisting off neutral and. reducing gases havinganoxygencontent-insuliicientf to cause visible formation, of; interferingamounts1 of nickel; oxide dross on the` surfaceA of the bath whenl its,sulfur; content ist still substantial but is less; than` about,V 4% andIitsf oxygen con-l tent is. at.- least sufficient. to oxidize the, sulfurcen-tent, the bath being.` maintained ina tnrbnlentzstate by nen-`nnenrnatie. induced: asitatien'nndf at a bien temeer-attire sntiicient,te; minimize. tbeterrnatien et. oxide dress en tbe surface-,i nf: the;nieleelnepree alley. beth. nnen, c bensfL ing frein Oxygen-cicli; gases;and; maintaining the bien temperature in tbe, beth. in tbe. presence.ciy said bet ariseste. centinne tbe reaction between sulfur; and.Oxygen. in. thetnrbnlent; beth and te, Produce nickel-copper.- allerwith, al sulfur.. content loWl uQllgh below 0.5,% for re-A moval; b y.desulfurizatiorn.

8, An Aimproved process, for eliminating` copper. from` andautogenously, smelting, a n iclel sulfide. materialcontainingcbpertovnr-ednce refined, nignickel ci lewfsnlinr contentwhich comprises` melting and mixing between abcnt ene-half tedenble-byweishtei a; mixture ct sedinrn chloride, and, sodiumv sulfide. salt-swith; said nickel sulfide materiel-in the ineltenI state; allowing saidmelten innss` seperate ntog en upper center-richand` sodium salt-`containing liquid phase. and a lower nickel` sulfide liquid pbase;sernratina seid liquid nbasesz. trentina said' Unger liquidphaseforrecovery of the sodium salts contained therein; oxidizing andremoving sodium salts from the lower, nickel sulfide liquid phase;directing 4oxygen onto the exposed surface of la molten bath of saidnickel sulfide phase, while avoiding sidewall and bottom blowing of saidoxygen through the bath, and maintaining the bath `during the smeltingin a state of turbulence with mechanically induced agitation, saidagitation being maintained during the directing of 4said oxygen, topromote intimate and eiiicient gas-liquid-solid contact and uniformdistribution of oxygen throughout the bath and its rapid reaction withsulfur therein; raising the bath temperature as desulfurization proceedsto more than about 2800 F. while continuing the directing of oxygen ontothe bath; changing said oxygen being directed onto the molten bath tohot gases from the group consisting of neutral and reducing gasessubstantially free of sulfur dioxide and having an oxygen contentinsufficient to cause visible formation of interfering amounts of nickeloxide dross on the surface of the bath when its sulfur content isbetween about 1% and about 3% and its oxygen content is at leastsufiicient to oxidize the sulfur content, the bath being at atemperature of at least about 3000u F. and maintained in a turbulentstate by mechanically induced agitation upon said changing from oxygen;and maintaining a bath temperature of at least about 3000 F. in thepresence of said hot gases to continue the reaction between sulfur andoxygen in the turbulent bath and to produce refined, pig nickel with alow sulfur content of not more than of the order of about 0.05%.

9. In the treatment of a nickel sulfide material with a copper contentof at least about 0.50% for elimination of the copper and recovery ofthe nickel contained therein, the improvement which comprises meltingand mixing between about one-half to double by weight of a salt mixtureof sodium sulfide and a metal chloride from the group consisting ofsodium chloride, potassium chloride, calcium chloride and aluminumchloride with said nickel sulfide material inthe molten state; allowingsaid molten mass to separate into an upper copper sulfide-salt mixtureliquid phase and a lower nickel sulfide liquid phase; separating saidliquid phases; treating said upper liquid phase for recovery of the saltmixture contained therein; oxidizing and removing salt mixture from thelower, nickel sulfide liquid phase; and treating said nickel sulfideliquid phase for recovery of the nickel contained therein.

10. A process as described in claim 9 in which the salt mixture issodium chloride and sodium sulfide and contains between about 25% andabout 75% sodium chloride, the separation of the copper sulfide-saltmixture phase and the nickel sulfide phase is carried out in aliquidliquid extraction column and the nickel sulfide phase separatedout contains less than 0.10% copper.

ll. In the treatment of a nickel sulfide material with a copper contentof at least about 0.50% for elimination of the copper and recovery ofthe nickel contained therein, the improvement which comprises meltingand mixing between about one-half to double by weight of a mixture ofsodium chloride and sodium sulfide salts containing between about 25 andabout 75% sodium chloride with said nickel sulfide material in themolten state at a temperature of not below about 1350" F. and not aboveabout 1550 F.; allowing said molten mass to separate into an uppercopper sulfide and sodium salt-containing liquid phase and a lowernickel sulfide liquid phase with a copper content of less than about0.10%; separating said upper and lower phases by pouring one from theother in the liquid state; treating said upper liquid phase for recoveryof the sodium salts contained therein; reverting said sodium salts forfurther copper elimination; oxidizing and removing any sodium salts fromthe lower, nickel sulfide liquid phase; and treating the nickel sulfideremaining for recovery of the nickel contained therein.

12. In the treatment of cobalt-containing nickel sulfide material with acopper content of at least about 0.50% for elimination of the copper andcobalt and recovery of the nickel contained therein as refined, pignickel of low sulfur content, the improvement which comprises meltingand mixing between about one-half to double by weight of a salt mixtureof sodium sulfide and a metal chloride from the group consisting of thechlorides of sodium, potassium, calcium and aluminum with said nickelsulfide material in the molten state; allowing said molten mass toseparate into an upper copper sulfidesalt mixture liquid phase and alower nickel sulfide liquid phase; repeating the foregoing operations ina countercurrent manner; separating the final liquid phases; treatingthe upper liquid phase for recovery of the copper and the salt mixturecontained therein; oxidizing and removing salt mixture from the final,lower, nickel sulfide liquid phase; directing commercial oxygen onto theexposed surface of a molten bath of said nickel sulfide from whichcopper has been eliminated, While avoiding sidewall and bottom blowingof said oxygen through the bath, and maintaining the bath in a state ofturbulence by mechanically induced agitation, said agitation beingmaintained during the directing of said oxygen, to promote intimate andefficient gas-liquid-solid contact and uniform distribution of oxygenthroughout the bath and its rapid reaction with sulfur therein;maintaining the sulfur content of the molten bath at more than about 3%by adding substantially copper-free fresh nickel sulfide material, whileblowing with oxygen at between about 2300 F. and about 2800 F. tooxidize the cobalt and remove it as slag; raising the temperature of themolten bath when cobalt has been eliminated and slagged off and asdesulfurization proceeds to more than about 2800 F. while continuing thedirecting of oxygen onto the bath; changing said oxygen being directedonto the molten bath to hot gases from the group consisting of neutraland reducing gases substantially free of sulphur dioxide and having anoxygen content insufiicient to cause visible formation of interferingamounts of nickel oxide dross on the surface of the bath when its sulfurcontent is still substantial but is less than about 4% and its oxygencontent is at least sufficient to oxidize the sulfur content, the bathbeing at a temperature of between about 3000 F. and 3200 F. andmaintained in a turbulent state by mechanically induced agitation uponsaid changing from oxygen; and maintaining a bath temperature of betweenabout 3000" F. and 3200 F. in the presence of said hot gases to continuethe reaction between sulfur and oxygen in the turbulent bath and toproduce refined, pig nickel with a low sulfur content of not more thanof the order of about 0.05%.

References Cited in the file of this patent UNITED STATES PATENTS1,599,424 Lellep Sept. 14, 1926 `1,623,797 Lellep Apr. 5, 1927.1,703,329 Wilenchik Feb. 26, 1929 1,877,928 McGregor Sept. 20, 19322,396,792 Kroll Mar. 19, 1946 2,598,393 Kalling et al May 27, 19522,653,868 Lichty Sept. 29, 1953

1. AN IMPROVED PROCESS FOR AUTOGENOUSLY CONVERTING A NICKEL SULFIDEMATERIAL TO PRODUCE NICKEL OF LOW SULFUR CONTENT WHICH COMPRISESDIRECTING OXIDIZING GASES FROM THE GROUP CONSISTING OF COMMERCIAL OXYGENAND OXYGENENRICHED AIR INTO THE EXPOSED SURFACE OF A MOLTEN BATH OF SAIDSULFIDE MATERIAL, WHILE AVOIDING SIDEWALL AND BOTTOM BLOWING OF SAIDGASES THROUGH THE BATH, AND MAINTAINING THE BATH DURING THE CONVERTINGIN A STATE OF TURBULENCE WITH NON-PNEUMATIC, MECHANICALLY INDUCEDAGITATION, SAID AGITATION BEING MAINTAINED DURING THE DIRECTING OF SAIDOXIDIZING GASES, TO PROMOTE INTIMATE AND EFFICIENT GAS-LIQUID-SOLIDCONTACT AND UNIFORM DISTRIBUTION OF OXYGEN THROUGHOUT THE BATH AND ITSRAPID REACTION WITH SULFUR THEREIN; RAISING THE BATH TEMPERATURE ASDESULFURIZATION PROCEEDS TO MORE THAN ABOUT 2800*F., CHANGING SAID GASESBEING INTRODUCED INTO THE BATH SURFACE TO HOT, SUBSTANTIALLY SULFUR-FREEGASES FROM THE GROUP CONSISTING OF NEUTRAL AND REDUCING GASES HAVING ANOXYGEN CONTENT INSUFFICIENT TO CAUSE VISIBLE FORMATION OF INTERFERINGAMOUNTS OF NICKEL OXIDE DROSS ON THE SURFACE OF THE BATH WHEN THE SULFURCONTENT OF THE BATH IS STILL SUBSTANTIAL BUT IS LESS THAN ABOUT 4% ANDTHE OXYGEN